"The incongruity between the treatment of cash and cryptocurrency"
Cash is very different from cryptocoins. Cash is real. It's right there in your hands, and there are tools to check if it's legit.
With virtual money, I think it is a good idea to have more checks and controls. It ensures that the market is going to stay safe.
But I would like somebody to explain to me the notion of "stablecoin". I get BitCoin - you churn some software long enough and you get a coin, which you can then use or sell for it's current market value which is established by supply and demand. But how can you "add" virtual coins to state money without either pushing the system out of whack or being guilty of counterfeiting ?